Enhanced-Linearity Wideband Full-Duplex Receiver With Shared Self-Interference Canceller

Abstract

A wideband full-duplex (FD) receiver with enhanced-linearity technique and shared self-interference cancellation (SIC) is implemented in a 40-nm CMOS process. By combining Hilbert-transform-equalization (HTE)-based self-interference (SI) canceller and translational loop, an FD receiver with RF domain cancellation is presented with an extra auxiliary cancellation path by reusing the mixer in the translational loop. By introducing the auxiliary path, the influence of SI circuit to receiver front end is minimized. Meanwhile, a self-loaded linearization technique with acceptable noise degradation and extra power consumption is proposed to be employed in the FD receiver for both receiver and SI canceller. Due to the 2-D regulation, such a technique can achieve a relatively robust linearity improvement and bring flexibility to circuit design. The measurement results show that the proposed FD receiver operates across 0.8–3.5 GHz with a gain of 29.0–31.8 dB and a noise figure of 3.68–5.23 dB. The proposed linearization technique achieves 3.2–4.7-dB linearity improvement for receiver with only 0.45–0.64-dB NF degradation. In addition, the canceller with the proposed linearization method achieves RF domain delays ranging from 1.59 to 4.03 ns while demonstrating more than 6.33-dB linearity improvement. With the implementation of self-loaded technique and shared SIC, a greater than 23.4-dB RF domain SI suppression is measured across 40-MHz bandwidth (BW) with 64-QAM modulated signals in a circulator-based setup for the SIC scheme in this work with RX noise degradation of less than 1.38 dB.